Seriously, you can't save cookies offline? I usually don't develop sites that benefit from cookies, so I've never run into this. But there is a note in the Sony documentation that says that it only allows a certain number of cookies per domain (I think 3), so I wonder if the problem isn't related to that limitation.
In any case, if you absolutely need to use your app on a PSP and you absolutely need to save data offline, I would completely suggest the "abandon flash" route. You suggest various homebrew sollutions, but seriously, the greatest advantage of Flash is that it's available to non-homebrew users, and if you're going to pursue C/C++/Lua sollutions to help overcome this limitation, then you might as well ditch Flash altogeather and just take care of your business in one of those less restricted languages.
The PSP web browser does offer a few native functions for returning data from JavaScript (so you could build a web page that hosts your Flash app, and then when it comes time to save data to the Memory Stick you could append the data to the search string of the address of a seperate page that contains the JavaScript code to extract that data and then use the PSP specific functions to write that data out to the Memory Stick), HOWEVER, these functions are NOT available in the default browser as accessed via the XMB. You would have to build a wrapper EBOOT containing a C function that would call the browser, passing the browser all of the nessecary data to enable this functionality. The good news is that any such C program could get away with minimal coding, allowing you to focus solely on the ActionScript/JavaScript side, but the bad news is that you would still need a homebrew-enabled PSP to use it. It seems fairly obvious that Sony has to have official API calls for calling the browser from a C function, but I am completely unaware of whether or not anyone in the homebrew community has uncovered the syntax for those call(s) yet. Seems like it would be fairly trivial to uncover, so maybe somebody does know the process, or for that matter, would be willing to investigate it for you. Just need to find some application (other then the XMB) that calls the NetFront browser and then reverse engineer it to find the methouds it uses to do so.
Of course it may also be possible to do what you're talking about (via sendAndLoad) in custom firmware by creating a prx that starts up whenever the browser is called and sits there monitoring ActionScript activity, handling any statements that it's set to watch for, but that would be entirely dependent on whether or not any such prx would be capable of intercepting ActionScript calls, and whether or not it could watch for the requested calls efficiently.
Either way, I'd say that there are some (homebrew dependent) avenues that you could pursue that would result in a usable workaround, the only question I would have in your situation is "do I absolutely need to use Flash to accomplish this task?" My guess is that if you don't need to use the networking functionality of the browser (which I'm guessing you don't since you pointed out the offline cookie limitation), then you're probably much better off just developing in another langauge. Even Lua can write data to the Memory Stick and is much less hampered by memory limitations anyway. I'd only seriously consider Flash for apps that:
a) Absolutely don't need to write to the Memory Stick,
b) Would significantly benefit from the convenient networking functionality of the NetFront browser
or,
c) Would benefit from HTML integration
Other then that, I just don't see Flash apps being worth the hassle of their limitations.
Bookmarks